mill creek/peaks branch/state-

Mill Creek/Peaks Branch/State-Thomas Drainage Relief Tunnel

Sarah Standifer, DirectorTrinity Watershed Management

Mobility Solutions, Infrastructure & Sustainability Committee

January 22, 2018

Overview• Project Summary• Project Benefits• Project Background/Concerns• Project Timeline• Project Bid Information• Staff Recommendation

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Mobility Solutions, Infrastructure & Sustainability


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Project Summary • Consists of five-mile, 30-foot diameter tunnel• Constructed 70-100 feet below ground• Minimum disturbance to surface properties • Construction costs approximately $200 million• Construction will last around five years• Approved by voters in two bond elections (2006

and 2012)

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Deep Tunnel Construction

• Utilizes Tunnel Boring Machine to mine deep tunnel

• Advantages to tunneling

• Minimizes street and traffic impacts

• Minimizes utility relocations


Benefits of the Drainage Tunnel • Increases public safety• Relieves repeated flooding• Protects residential and commercial properties• Reduces impacts to mobility networks• Upgrades drainage system

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Drainage Basin Information

Basin Areas• Mill Creek (2,200 ac.)• Peaks Branch (3,100 ac.)• East Peaks (1,100 ac.)• State-Thomas (450 ac.)


Areas Currently Subject to 100-Year Flood

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Areas Subject to 100-Year Flood after Tunnel Construction

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Project Drivers • Drainage studies in

these areas conducted in 1970s, 1980s, and 1990s

• Initial phase of larger drainage master plans for Mill Creek and Peaks Branch

• Existing storm sewers from the 1930s are inadequate for large storms

• Many areas flooded in 1995, 2006, 2007, 2009, 2012, and 2015


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Project Drivers, cont’d • Tunnel provides outfall

for future improvements• M Streets• Upper Peaks Branch

• Tunnel reduces flooding in areas including:

• 2,200 properties• $4B property value (2015)

• Project approved by voters in two bond elections (2006 and 2012)


Project Timeline • 2006 – Mill Creek, Peaks Branch and State-Thomas

drainage improvements approved as separate projects in Bond Program

• 2009 – Mill Creek and Peaks Branch tunnel plans approved

• 2012 – State-Thomas tunnel extension approved• 2012 – Construction funding approved in Bond

Program• 2015 – Construction advertised and bids received• 2016 – Construction bids rejected and re-

advertisement approved• 2017 – Construction re-advertised and bids received

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Project Specifications RevisionsFrom First Advertisement to Second• Included deductive alternatives

• State-Thomas tunnel extension• Dewatering pump station• Dewatering pump station shaft• Inlet shaft “C”

• Expanded bidder experience qualifications to possibly attract more bidders

• Revised number of completed projects from three within a five-year period to two within a 10-year period

• Added minimum tunnel length of 5,000 feet• Revised diameter of tunnel from 20 feet to 18 feet

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Project Safety Requirements• Contractor requirements

• Provide written, sealed Health and Safety Plan• Established safety training program• Emergence response procedures

• Provide certified safety professional dedicated to implementation and supervision of work safety

• Provide safety representative at shaft and tunnel sites• Construction Manager oversight• Review contractor’s Health and Safety Plan

• Inspect contractor work areas for safety compliance• Provide on-site safety reviews by Safety Manager

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Project Bid Information • Received three bids on September 8, 2017

• Southland Mole JV – $206,700,000• Michels Tunneling – $224,870,637• C.M.C. di Ravenna – $237,072,871

• Received bid protest from a bidder• Unbalanced bid protest evaluated by staff and

consultants• Found bid protest to be without merit

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Project Bid Review • City Auditor’s Attestation Report on Agreed-Upon

Procedures for Construction Bid Evaluation• Project was bid as a low-bid construction project• Found exceptions that were remedied by departments

during the bid review• Found exception in experience requirement of low

bidder• As documented for project #2, tunnel construction was

completed in 2005• Other work, including shaft, was ongoing in 2007, within the

experience timeframe

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Staff Recommendation • Proceed with award of construction to low bidder

• Southland Mole JV – $206,700,000• Funding from General Obligation bonds

• Project is ready to award for construction• Funding is available• Right-of-way and subsurface easements are acquired

• One subsurface easement pending

• City Council consideration of construction award on February 14, 2018

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Sarah Standifer, DirectorTrinity Watershed Management

Mobility Solutions, Infrastructure & Sustainability Committee

January 22, 2018

mill creek/peaks branch/state-

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